Let-back mechanism for looms.



G. LAVALLEE.

LET-BAGK MECHANISM FOR LOOMS.

APPLICATION FILED JUNE 27,1908.

907,378. Patented Dec. 22, 1908.

2 SHEETS-15321 1,

I 'I- E5555- I E T: if i dfgifi c. LAVALLEB, LET-BAGK MECHANISM FOR LOOMS.

APPLICATION FILED JUNE 27,1908- Palfented Dec. 22, 1908.

2 SHEETS-SHEET 2.

VA a wasmunmu, v, c.

CHARLES LAVALLEE, OF NEW MARKET, NEW HAMPSHIRE.

LET-BACK MECHANISM FOR LOOMS.

Specification of Letters Patent.

Application filed June 27, 1908.

V Patented Dec. 22, 1908.

Serial No. 440,621.

To all whom it may concern:

Be it known that I, CHARLES LAVALLEE, a subject of the King of Great Britain, residing in New Market, in the county of Rockingham and State of New Hampshire, have invented a new and useful Improvement in Let-Back Mechanisms for Looms, of which the following is a specification.

This improvement relates to that class of inventions or devices in which when the take-up of the cloth is stopped by the detection of a technically thin place produced by an absence of" filling, the cloth is let back in. order that when the fresh filling is laid it will by the stopping of the take-up and the letting back of the cloth be resumed where the old filling failed.

, The present invention relates to a certain novel construction and arrangement of parts, fully described below, and illustrated in the accompanying drawings, whereby an im proved mechanism for the purpose is produced which is applicable to diflerently constructed looms, whereby a more perfect adjustment of the device and its parts are provided, and whereby the efficiency of the operation is enhanced.

In the drawingsFigure 1 isan elevation of a portion of one end of a loom, showing a part of a take-up mechanism, and. with my improved let-back mechanism a plied and in its normal position, that is, wit 1 the loom operating normally. Fig. 2 is an enlarged view in detail showing in dotted lines my improved let-back mechanism in the position assumed when the filling is absent, and show ing in full lines the position of the parts when the machine is ready to start and let back the cloth. Fig. 3 is a detail of the segment-rack removed. Fig. 4 is an end view of the letback mechanism. Fig. 5 is a section taken on line 55, Fig. 1.

Similar letters of reference indicate corresponding parts.

0 represents a portion of the. frame of a loom of well known construction, and bis the cloth supported by a suitable take-up of which 0 is a ratchet-wheelmaking a part of the pick-gear and sup orted by the frame. (1 represents the cam-s aft on which is rigidly secured an eccentric e from which the arm f extends into engagement with the take-up-wheel or ratchet-wheel c by means of a suitable pawl indicated by dotted lines at g. All these parts are well known and operate in the manner common in the art, and

require no detailed explanation. I do not confine myself to their exact construction and arrangement, except so far as such construction and arrangement are necessary to the operation of my invention.

Rigid on the usual rock-shaft his an arm 76 whose outer end is adjustably and rigidly se-,

cured by a suitable bolt 1'. to the outer end of a bar Z by means of a slot m therein, small cars it being preferably provided on the arm 76 and resting on the up er surface of the bar I. This bar Z is forme at its opposite end into an integral hook 0, and it is provided between the hook and the slotted portion with a pivot 19 which extends through an elongated slot g (see Fig. 3) in a segment-rack 1 which is thus rendered capable of vertical movement with relation to the pivot. This rack is supported by the pivot 19 between the bar Z and a back-plate s, also supported by said pivot. The lower edge of the bar Z is provided with a tooth t, and with a notch u at the rear of the tooth; the segment-rack r is provided with an integral pawl 11 adapted to e engaged or held by the tooth t by means of its horizontal extension. 1) and the notch u, and is provided also with a horizontal looking rojection w ada ted to be engaged in the hoo o; and the bac '-plate 8 has at its upper end an integral holding-pawl :0 adapted to engage the ratchet-teeth on the upper edge of the segment-rack, and a horizontal stop at its lower end. Asto 2 (Fig.4) extends horizontally fromthe en of the bar I behind the'rear edge of the segment-rack r.

In operation, when the loom is working the parts are as illustrated in Fig. 1, the bar I being down, the holding-pawl o slipping over the teeth on the ratchet-wheel c and preventing said wheel from rotating in the opposite direction, the part c of the holding-pawl is in the notch a and held in position by the tooth t, the locking projection w is in engagement with the hook 0, and the back-plate is ad'usted by means ofa suitable nut on the bolt p so as to be rigid with the bar I and en.- gage by means of the hold-back or stop a: the desired tooth on the upper side of the segment-rack 1". In the drawings the tooth engaged is the third tooth from the end, but the.

bar is adjusted to engage such tooth as is ad- ,visable according to the loom to which the let-back mechanlsm is attached.

When the filling breaks, the rock-shaft h is rotated by the filling-sto -motion in the ordinary manner and lifts t 1e let-back mechanism by means of the usual arm is, lifting the bar Z with its hook 0, the segment rack, and the entire let-back mechanism into the position indicated by dotted lines in Fig. 2. Then the parts are thus lifted, the segmentrack 1" drops by gravity as far as the elongated slot 9 will allow out of engagement with the hold-back or stop x, and with its locking projection w and pawl 0 out of engagement with the hook 0 and recess it. As the greater part of the weight of the rack is at the left of the pivot p, the rack swings toward the right until the pawl o rests against the stop y, all as shown in the dotted lines. The backplate 3 remains rigid with the arm Z.

When the loom is ready to start, the parts are in the position indicated in full lines in Fig. 2, and when the loom is started the dropping of the let-back mechanism produced by the downward swing of the arm 70 from the position indicated in full lines in Fig. 2 to that illustrated in Fig. 1 allows time for the segment-rackr (which by means of the slot q extends considerably below the bar Z) to let back the ratchet-wheel c the de sired number of picks, until the hold-back a: is lowered into engagement with the rack which has been rotated until the pawl o v is again in engagement with the ratchet-wheel and the tooth t, the stop w in engagement with the hook 0, and the stop 2 (Fig. 4) bears against the plain or rear edge of the segmentrack, thus preventing a thin place in the cloth.

It will readily be seen that the substantially vertically slotted segment-rack in connection with the rotatively adjustable backbar 1', remlers it possible to adjust the letback mechanism to the desired number of teeth and picks, provides means for accurate timing of the'rack as it descends in advance of the rest of the let-back mechanism, and renders the mechanism applicable to looms of different constructions.

Having thus fully described my invention, what I claim, and desire to secure by Letters Patent, is

1. In a let-back mechanism of the character and for the purpose described, a bar adapted to be secured to and be operated by the arm extending from the rock-shaft of a loom, a hook on the end of the bar opposite that which is connected with said arm, a tooth extending downward from the lower edge of the bar, a back-plate formed at its upper end with a horizontal hold-back or stop, a segment-rack between said bar and back-plate and formed with teeth on its upper edge adapted to be engaged by the holdback and teeth on its lower edge, said segment-rack being provided with an elongated slot, a locking projection extending horizontally from the segment-rack into normal engagement with the said hook on the end of the bar, a bolt extending from the bar through the slot in the segment-rack to the back-plate and holding said back-plate and bar adjustably in rigid connection, a pawl extending from the lower edge of the segment-rack and adapted to be normally in engagement with a ratchet-wheel in the takeup mechanism, and a horizontal extension integral with said pawl extending into normal engagement with the tooth which extends downward from the lower edge of the bar.

2. In a let-back mechanism of the character and for the purpose described, a bar adapted to be secured to and be operated by the arm extending from the rock-shaft of a loom, a hook on the end of the bar opposite that which is connected with said arm, a tooth extending downward from the lower edge of the bar, a back-plate formed at its upper end with a horizontal hold-back or stop, a segment-rack between said bar and back-plate and formed with teeth on its upper edge adapted to be engaged by the holdback and teeth on its lower edge, said segment-rack being provided with an elongated slot, a bolt extending from the bar through the slot in the segment-rack to the, backplate and holding said back-plate and bar adjustably in rigid connection, a stop extending horizontally from the upper portion of the segment-rack and adapted to be engaged in said hook, a'stop extending horizon.- tally from the lower end of the back-plate and adaptedto limit the rotation of the segment-rack, a stop extending from the rear side of the hooked end of the bar behind the segment-rack, a pawl extending from the lower edge of the segment-rack and adapted to be normally in engagement with a ratchetwheel in the take-up mechanism, and a horizontal extension integral with said pawl extending into normal engagement with the tooth which extends downward from the lower edge of the bar.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

CHARLES LAVALLEE.

Witnesses:

WILFRED D. PARISEAU, JONATHAN WALKER. 

